Senior Backend Engineer

This team is investing in its centralized experimentation platform which powers A/B testing across web and native applications. This platform enables teams to design, launch, and analyze experiments that improve customer experience and business outcomes. This role focuses on building and scaling backend services and APIs that support experiment configuration, variant assignment, analytics, and reporting. You will work on systems that enable real-time decisioning, handle high-throughput traffic, and integrate with analytics and data platforms at enterprise scale. We are seeking a Senior Backend Engineer (Node.js) to design and build distributed systems powering experimentation workflows and real-time experimentation services. What You’ll Work On Design and build scalable Node.js / TypeScript services supporting experimentation workflows Develop APIs for experiment lifecycle management (create, configure, launch, monitor) Build services for variant assignment and real-time decisioning Support server-side experimentation and advanced testing models (e.g., multi-armed bandits) Build systems handling large-scale traffic and real-time experiment evaluation Optimize services for low latency, high availability, and resilience Integrate with clickstream, analytics, and monitoring platforms Design data flows for experiment tracking, metrics computation, and reporting Partner with data engineering and data science teams to ensure accurate experiment measurement Contribute to evolving the platform toward a decoupled, scalable architecture Help build new services such as centralized variant assignment systems Collaborate cross-functionally with product, UX, and engineering teams Must Haves Skills 5+ years of backend software engineering experience Strong proficiency in Node.js (JavaScript/TypeScript) Experience building RESTful APIs and distributed services Experience with backend frameworks (Express, Koa, or similar) Strong understanding of distributed systems, scalability, and performance optimization Experience with cloud-native architectures (Kubernetes, GCP, or similar) Experience with databases and data modeling (NoSQL such as MongoDB) Distributed Systems & Performance Experience designing systems for high throughput and low latency Strong understanding of scalability, resilience, and performance optimization Ability to support real-time decisioning systems APIs & Integration Experience building and maintaining RESTful APIs Integration with analytics, monitoring, and data platforms Ability to design systems that support experiment configuration and execution workflows Data & Experimentation Systems Experience with data modeling and NoSQL databases (e.g., MongoDB) Familiarity with experiment tracking, metrics computation, and reporting pipelines Ability to design data flows for analytics and experimentation platforms Nice to Have Experience with A/B testing, feature flagging, or experimentation platforms Experience implementing variant assignment or feature rollout systems Familiarity with event-driven architectures and streaming pipelines Exposure to analytics pipelines or experimentation metrics Experience working in multi-language environments (Node, Go, Python) Knowledge of eCommerce platforms and customer experience optimization What Success Looks Like Scalable backend services supporting enterprise experimentation workflows Reliable systems enabling real-time experiment decisioning at scale High-performance services handling millions of users and high traffic volumes Accurate and scalable experiment tracking and analytics pipelines Continued evolution toward a decoupled, centralized experimentation platform Show more Show less